Lateral Patellofemoral Ligament Research Articles

Effect of soft tissue tension around the knee joint on medio-lateral patellar position

Patellofemoral pain (PFP) is one of the most common sports injuries of the knee joint and has a high persistence and recurrence rate. Medio-lateral patellar position in the knee extension position during contraction is associated with PFP. However, soft tissue tension that most influences the medio-lateral patellar position in the knee extension position during contraction in vivo is unclear. We aimed to clarify the relationship between medio-lateral patellar position and soft tissue tension around the knee joint. Twelve patients with PFP and 20 healthy participants were included. Medio-lateral patellar position and tension of the rectus femoris, vastus lateralis (VL), vastus medialis, iliotibial band (ITB), lateral patellofemoral ligament, and medial patellofemoral ligament were measured during contraction and rest. The tensions of the VL and ITB during contraction and the medio-lateral patellar position at rest were significantly associated with medio-lateral patellar position during contraction (β = 0.449, 0.354, and 0.393, respectively). In addition, the tension of ITB was significantly associated with the medio-lateral patellar position at rest (β = 0.646). These relationships were not affected by the presence of PFP. These findings suggest that the patellar position during contraction became more lateral as the tension in the VL and ITB increased, regardless of the presence of PFP. These results may facilitate the prevention and treatment of PFP.

Medial Patellofemoral Ligament and Lateral Patellofemoral Ligament Reconstruction after Tibial Tuberosity Transposition in a Young Woman with Patellar Instability

In patients with reccurent lateral and medial patellar instability, isolated medial patellofemoral ligament (MPFL) reconstruction may be insufficient due to poor lateral retinacular tissue quality. In this report, we describe a case of a patient that underwent simultaneous MPFL and lateral patellofemoral ligament (LPFL) reconstruction on the left knee due to chronic bidirectional patellar instability. A 29-year-old female patient presented with first-time lateral patellar dislocation five years ago due to acute strain. She underwent a tibial tuberosity transposition in another hospital. After the surgery, she suffered from recurrent medial and lateral patellar dislocation and presented to our center. MPFL and concomitant LPFL reconstruction on the left knee was simultaneously performed due to bilateral patellar dislocation. The patella was stable postoperatively, and the patient underwent physiotherapy with successful results to date. Single-time patellar dislocation should be treated conservatively. Surgical treatment after the first episode of dislocation can magnitude the risk of postoperative complications. The simultaneous reconstructing of the LPFL yields patellar fixation indistinguishable from the native LPFL. These grafts provide separate tensioning depending on body anatomy, allowing for individualized stability. Anatomical MPFL reconstruction is supported by well-established high-quality research. Reconstructing the LPFL anatomically yields patellar fixation indistinguishable from the native LPFL.

Surgical Technique for Lateral Patellofemoral Ligament Reconstruction Using Bone Tunnels: A New Method.

Medial patellar instability (lateral patellofemoral ligament tear) is a rare condition which is commonly associated with lateral release for lateral patellar instability. LPFL is a lateralstabilizer of the patellofemoral joint. Reconstruction of LPFL is necessary to provide stability to the patella-femoral joint in patients with instability. We describe a novel technique of trans-osseous reconstruction of LPFL to gain stability and have better graft incorporation. A doubled peroneus longus graft is inserted into the patellar tunnel and secured with an endo button on the anteromedial aspect of the patella; the other end is then inserted into the insertional point on the femur and secured with an interference screw. This is an easy, novel, and reproducible technique which can be used to reconstruct LPFL.

Lateral Patellofemoral Ligament Reconstruction: Anatomy, Biomechanics, Indications, and Surgical Techniques

Lateral Patellofemoral Ligament Reconstruction: Anatomy, Biomechanics, Indications, and Surgical Techniques

Lateral Patellofemoral Ligament Reconstruction: A Biomechanical Comparison of 2 Techniques

Background: The importance of maintaining lateral patellar stabilizing structures has been demonstrated by the presence of iatrogenic medial patellar instability after lateral retinacular release (LRR) procedures. In patients with medial patellar instability, lateral patellofemoral ligament (LPFL) reconstruction has been clinically shown to restore patellar stability while improving patient-reported outcomes. However, the biomechanics associated with different LPFL reconstruction techniques remain largely unknown. Purpose: To (1) investigate whether LPFL reconstruction restores medial patellar translation compared with the intact state after LRR and (2) evaluate for any biomechanical differences between soft tissue and osseous LPFL reconstruction techniques. Study Design: Controlled laboratory study. Methods: A total of 7 knees were included in the final analysis. The knees were dissected, and the tibia and femur were potted. An eye screw was then placed at the midpoint of the patella perpendicular to the medial surface. A custom jig was constructed to allow for a 1-kg load to be applied to the quadriceps muscle. Medial patellar displacement was investigated at 0°, 10°, 20°, 30°, 45°, 60°, and 90° of knee flexion using a tensile testing machine with a 20-N medial force applied to the patella. Medial patellar displacement was assessed in 4 states: intact, LRR, soft tissue LPFL reconstruction (inserted through incisions in the iliotibial band, quadriceps tendon, and patellar tendon), and osseous LPFL reconstruction. Results: The LRR group had significantly greater medial patellar translation compared with the intact group throughout flexion (P < .01 to P = .029). The soft tissue LPFL reconstruction group demonstrated significantly greater medial patellar translation at 30° (P = .020) and 45° (P = .025) compared with the intact group, with less translation compared with the LRR group at all degrees of knee flexion except for 45° (P = .065). The osseous LPFL reconstruction group demonstrated significantly greater medial patellar translation compared with the intact group at 30° of flexion (P = .036), with significantly less translation compared with the LRR group from 0° to 30° (P < .01 to P = .013). The soft tissue LPFL reconstruction group (15.94 ± 2.55 mm) demonstrated significantly greater medial patellar translation at 10° of flexion compared with the osseous LPFL reconstruction group (14.16 ± 2.34 mm) (P = .033). Conclusion: Soft tissue LPFL reconstruction led to significantly greater medial patellar translation at 30° and 45° compared with the intact state, while osseous LPFL reconstruction produced significantly greater translation only at 30°. Both the soft tissue and the osseous reconstruction techniques resulted in comparable medial patellar translation at all degrees of knee flexion except for 10°, in which osseous reconstruction was more similar to the intact state. Clinical Relevance: Compared with LRR, soft tissue LPFL reconstruction was able to restore stability against medial patellar translation at most degrees of knee flexion, while osseous LPFL reconstruction did not provide adequate stabilization beyond 30° of flexion. While the LPFL does appear to have osseous insertions, soft tissue reconstruction functioned more similarly to the intact state after LRR.

Lateral Patellofemoral Ligament Reconstruction With Semitendinosus Allograft in the Setting of Previous Lateral Release

The lateral patellofemoral ligament acts to resist medial displacement of the patella. When medial subluxation occurs, it usually has an iatrogenic cause such as prior lateral release, an over-tightened medial patellofemoral ligament reconstruction, or detachment of the vastus lateralis from the patella. The justification for lateral retinacular release has historically been to address extensor mechanism issues such as imbalance of the mechanism due to increased retinacular tension. We present a Technical Note on the treatment of chronic medial patellar instability due to a previous lateral retinacular release using a soft-tissue reconstruction approach with a semitendinosus allograft.

A Comprehensive Description of the Lateral Patellofemoral Complex: Anatomy and Anisometry

Background: The lateral patellofemoral complex (LPFC) is an important stabilizer of the patella composed of the lateral retinacular structures including the lateral patellofemoral ligament (LPFL), the lateral patellomeniscal ligament (LPML), and the lateral patellotibial ligament (LPTL). While the isolated anatomy of the LPFL has been previously described, no previous study has investigated the entirety of the LPFC structure, length changes, and radiographic landmarks. An understanding of LPFC anatomy is important in the setting of LPFL injury or previous lateral release resulting in iatrogenic medial instability requiring LPFC reconstruction. Purpose: To both qualitatively and quantitatively describe the anatomy and length changes of the LPFC on gross anatomic dissections and standard radiographic views. Study Design: Descriptive laboratory study. Methods: Ten nonpaired cadaveric specimens were utilized in this study. Specimens were dissected to identify distinct attachments of the LPFL, LPML, and LPTL. Ligament lengths, footprints, and centers of each attachment were described with respect to osseous landmarks using a 3-dimensional coordinate measuring device. Ligament length changes were also assessed from 0° to 90° of flexion. Radiopaque markers were subsequently utilized to describe attachments on standard anteroposterior and lateral radiographic views. Results: The individual elements of the LPFC were identified in all specimens. The LPFL patellar attachment had an average total length of 22.5 mm (range, 18.3-27.5 mm), involving a mean of 59% (range, 50%-75%) of the sagittal patella. Based on the average patellar size, a mean of 63% of the LPFL attached to the patella, and the remainder (11.1 ± 1.4 mm) inserted into the patellar tendon. The femoral attachment of the LPFL had a mean maximum length of 24.4 ± 4.3 mm. The center of the LPFL femoral attachment was a mean distance of 13.5 ± 3.2 mm anterior and distal to the lateral epicondyle. The LPFL demonstrated significant shortening, especially in the first 45° of flexion (7.5 ± 5.1 mm). In contrast, the LPTL (5.5 ± 3.0 mm) and LPML (10.0 ± 3.3 mm) demonstrated significant shortening from 45° to 90°. On lateral radiographs, the center of the femoral attachment of the LPFL was a mean total distance of 19.2 ± 7.2 mm from the lateral epicondyle. Conclusion: The most important findings of this study were the correlative anatomy of 3 distinct lateral patellar ligaments (LPFL, LPML, and LPTL) and their anisometry through flexion. All 3 components demonstrated significant shortening during flexion. The quantitative and radiographic measurements detailed the LPFL osseous attachment on the patella; soft tissue attachment on the patellar tendon; and finally, the osseous insertion on the femur distal and anterior to the lateral epicondyle. Similarly, the authors documented the meniscal insertion of the LPML and defined a patellar insertion of the LPTL and LPML as a single attachment. These data allow for reproducible landmarks to aid in the understanding and reconstruction of the lateral patellar restraints. Clinical Relevance: The data produced from this investigation provide a comprehensive description of these 3 lateral patellar stabilizers (LPFL, LPML, LPTL). These data can be used intraoperatively to facilitate anatomic reconstructions of the lateral patellar stabilizers.

Are Patellofemoral Ligaments and Retinacula Distinct Structures of the Knee Joint? An Anatomic, Histological and Magnetic Resonance Imaging Study.

There is disagreement regarding the description of the patellofemoral ligaments (PFLs), considered by some authors as capsular thickening and by others as independent ligaments. It was hypothesised that the PFLs and retinacula are structures with different histological features. The aim of this study was to describe the stabilising structures of the patella in detail and to determine if the PFLs and retinacula are different and separable structures from a macroscopic, microscopic and imaging viewpoint. An anatomical study was performed on eight knees from five cadavers (mean age, 56.2 years; range, 35–63 years), and a histological study was conducted on specimens from nine patients having a mean age of 65 years (range 35–84 years) who had undergone surgical knee procedures. The imaging study was based on 100 MRIs (96 patients). The mean age was 46 years (range 16–88), and the study analysed the capsular-ligamentous structures. In the medial compartment, the layers and structures were as follows: superficial layer, medial retinaculum; intermediate layer, Medial Collateral Ligament (MCL), Posterior Oblique Ligament (POL) and Medial Patellofemoral Ligament (MPFL); deep layer, deep part of the MCL and joint capsule. In the lateral compartment, the layers and structures were the following: superficial layer, lateral retinaculum; intermediate layer, Lateral Collateral Ligament (LCL) and Lateral Patellofemoral Ligament (LPFL); deep layer, joint capsule. All of the knees examined presented a clearly distinguishable MPFL and LPFL separable from the capsular layer. Histological study: there was a higher density of nerve fibres in retinacula compared to ligaments (p = 0.0034) and a higher content of elastic fibres in retinacula (p < 0.0005). In imaging, there was no difference between medial and lateral retinaculum thickness (p > 0.05). In conclusion, both the lateral and medial compartment can be described using the three-layer scheme. PFLs and retinacula are separate structures both macroscopically and according to imaging analysis. The retinacula respond to their specific function with a higher nerve fibre content and higher number of elastic fibres compared to the ligaments.

Lateral Patellofemoral Ligament Reconstruction With a Hamstring Allograft

Background: Medial patellar instability is rare but may occur after lateral retinacular release. The lateral patellofemoral ligament is a significant stabilizer for medial and lateral patellar displacement, and soft tissue–based reconstruction may restore its stabilizing effect. Indications: Lateral patellofemoral ligament reconstruction (LPFLR) is indicated for patellar instability failing exhaustive nonoperative measures. Technique Description: Diagnostic arthroscopy for medial patellofemoral ligament (MPFL) status, patellar tracking, chondral status, and postoperative changes of lateral retinacular release is conducted. A 5-cm incision is made between the midpoint of the patella and the lateral epicondyle, or a single midline incision can be used if performing a concomitant MPFL reconstruction. Dissection is carried down to the lateral retinaculum and capsule, and two 1-cm incisions are made at the distal and proximal patella through the patellar and quadriceps tendon, respectively. The lateral epicondyle is then directly palpated, and two 1-cm incisions are made directly anterior and posterior to the epicondyle into the iliotibial band in full extension. A hamstring allograft is then shuttled in a V-shaped configuration from the quadriceps tendon through the iliotibial band and finally to the patellar tendon. Excess graft is trimmed and doubled over proximally and distally to replicate the normal (or contralateral) 0° to 15° of patellar eversion. Trial resting length and tension is set with temporary sutures through the proximal and distal doubled graft in full extension. The knee is taken through full range of motion to ensure there is no graft tightening in flexion or loosening in full extension. Eversion and patellar translation are then examined. Heavy nonabsorbable sutures are used to set length of the doubled allograft proximally and distally. Results: Case series of LPFLR have demonstrated significant improvements in patients’ pain, Lysholm score and Knee Injury and Osteoarthritis Outcome Score, and kinesiophobia with no instability events and normal range of motion at short-term follow-up. Discussion/Conclusion: Medial patellar instability can occur following lateral retinacular release and patients experiencing instability despite nonoperative treatment are likely to benefit from a soft tissue–based LPFLR. Although other nongraft-based techniques may confer similar outcomes, the authors find it more reliable to perform a lateral reconstruction as described.

Medial Patellofemoral Ligament Reconstruction With Concomitant Lateral Patellofemoral Reconstruction for Patellar Instability

Patients with bidirectional patellar instability who are unresponsive to conservative management may benefit from a medial patellofemoral ligament (MPFL) reconstruction and lateral patellofemoral ligament (LPFL) reconstruction. If an isolated MPFL reconstruction does not provide adequate stabilization intraoperatively, combined MPFL and LPFL reconstruction allows independent reconstruction, which can be performed with a facile, reproducible technique. The purpose of this report was to describe our technique for performing an MPFL reconstruction with a concurrent soft-tissue LPFL reconstruction combined with a distalizing tibial tubercle osteotomy to correct patella alta.

Specific surgical tactics features for the prevention of unsatisfactory total knee arthroplasty outcomes

The objective of the study was to improve the treatment results of patients with total knee arthroplasty (TKA) by substantiating and developing differentiated surgical tactics. The study included 151 patients (212 cases) who underwent TKA without patella replacement. The patients were divided into two groups: the main group is 74 patients (110 cases) and the comparison group is 77 patients (112 cases). In the main group, surgery was performed by using the developed installing tactics. The comparison group included the patients after the traditional surgical technique described in the manuals. There was no statistically significant difference between the groups (p = 0.52). The treatment results were assessed in 3, 6, 12, 24 months and more after surgery. KSS (Knee Society Score) and Kujala scales were used. The tactics of surgical intervention was developed, consisting of the correct installation of femoral and tibial components and capsular-ligamentous balancing of the patellofemoral joint. After the components implantation, the capsular-ligamentous balancing of the patellofemoral joint was performed depending on the patella position relative to the block of the femoral component (tilt, subluxation or dislocation of the patella). 5 types of patellar tendon extension were used: release of the lateral patellofemoral ligament, mobilization of the lateral skin flap from the capsule, “grid” type release, iliotibial tract release. The developed surgical tactics for TKA allowed us to obtain the better immediate and long-term treatment results than the traditional surgical technique. During the femoral and tibial component implantation, it is especially important to take into account the points that are directly related to the biomechanics of the patellofemoral part of the knee joint.

Noniatrogenic Medial Patellar Dislocations: Case Series and International Patellofemoral Study Group Experience.

Background:Most patellar dislocations occur in a lateral direction because of a summed lateral force vector and predisposing anatomic risk factors. Medial patellar instability is rare and is a well-recognized iatrogenic complication of an overly aggressive lateral retinacular release. Noniatrogenic medial patellar dislocations are rare. The management of these injuries is not well described.Purpose:To describe the experience of the International Patellofemoral Study Group with patients with noniatrogenic medial patellar dislocation.Study Design:Case series; Level of evidence, 4.Methods:Members of the International Patellofemoral Study Group (N = 64) were surveyed between October 2018 and April 2019. This group was chosen because of its wide referral base and interest in patellar instability. Specialists who had encountered a patient with medial patellar instability were sent a questionnaire inquiring about details of the case, including patient demographics, medical history, level of athletic competition, injury characteristics, and treatment. Cases were confirmed by physical examination records and, in some cases, with findings on advanced radiographic imaging.Results:The survey response rate was 73% (47/64). Three of the 47 specialists (6.4%) reported they had seen a case of noniatrogenic medial patellar dislocation, for a total of 6 cases. Four cases were described as recurrent medial dislocations in the setting of hypermobile Ehlers-Danlos syndrome; 2 were treated nonoperatively, 1 underwent lateral patellofemoral ligament reconstruction, and 1 underwent derotational osteotomies. Two medial-sided patellar dislocations in collegiate athletes were sports-related injuries that required surgical debridement but no ligamentous reconstruction. None of the patients had persistent or recurrent instability at the time of their most recent follow-up.Conclusion:Noniatrogenic medial patellar dislocations are extremely rare. This case review suggests that the treatment of first-time medial patellar instability in patients without known risk factors should follow the same principles as the treatment of lateral instability with no known risk factors, which is nonoperative management. For patients with documented risk factors and recurrence, surgery to address the risk factors may be appropriate.

A Case of Chronic Patellar Instability Following Failed Lateral Release

Case: The patient is a 25-year-old female with trochlear dysplasia, native left knee lateral patellar instability and iatrogenic medial patellar instability from treatment prior to presentation. She had grade 3 cartilage loss on the majority of her patellar articular surface. She underwent concurrent medial and lateral patellofemoral ligament reconstruction, Fulkerson osteotomy, and osteochondral allografting of her entire patellar articular surface. After reconstruction she had no further instances of instability.

The Anatomy and Length Changes of the Lateral Patellofemoral Ligament and Lateral Patellotibial Ligament

Objectives:The lateral patellar restraints (lateral patellofemoral ligament [LPFL], lateral patellotibial ligament [LPTL] and lateral patellomeniscal ligament [LPML]) are relatively poorly understood entities, which are important in patellar stability. The purpose of this study is to perform a qualitative and quantitative anatomic evaluation of the LPFL, LPML, and LPTL attachment sites, with specific attention to their relationship to pertinent osseous and soft tissue landmarks.Methods:Six non-paired, fresh frozen human cadaveric knees (n = 6) were utilized for this study. Institutional review board approval was not required for this cadaveric study. Knees were dissected and a variety of anatomic locations and the LPFL, LPTL, and LPML attachment sites and attachment centers were marked with surgical marker. The knee was placed in a custom jig and the quadriceps tendon was loaded with a 1 kg weight. Ligament area was measured with a portable coordinate measuring device (Microscribe, Solution Technologies, Oella, MD) and ligament centers were identified at 0, 15, 30, 45, 60 and 90° of flexion. The 3D location via a ‘bird’s eye view’ was calculated in Rhinoceros 5.0 software (McNeel North America, Seattle, WA). Data analysis was performed in MATLAB (MathWorks, Natick, MA) and Microsoft Excel (Microsoft, Redmond, WA). Statistical analysis was conducted with one-way repeated measure ANOVAs and Spearman Rank Correlation, which was used for non-normally distributed data, in SPSS (v26, IBM, Armonk, NY).Results:The location of the LPFL on the femur was compared to local landmarks (Fig 1). In the sagittal plane, the center, anterior, and posterior aspect of the LPFL were a mean of 17.0±1.4, 11.8±2.0, and 8.0±1.9 mm from the lateral epicondyle, respectively. Distances to the anterior, central, and posterior cartilage from these locations were 14.3±1.8, 14.6±2.9, and 14.3±3.3mm, respectively. The area of the LPFL was a mean of 31.59±20.24mm2 in the vertical plane. The location of the LPFL on the patella was then analyzed. The superior aspect of the LPFL was 8.52±2.74 mm from the superior pole of the patella, while the distance from the inferior pole to the LPFL was 14.01±4.53mm. The average length of the patella was 4.10±0.34cm and the LPFL occupied 45.09% of its sagittal length. The distance from the LPML to the anterolateral root was 7.35±2.98mm. The center of the LPTL on the tibia was a mean distance of 5.88±3.00mm from Gerdy’s tubercle. LPFL length decreased in flexion with a mean length of 40.60±3.24mm at 0°, 36.27±6.29mm at 15°, 33.77±4.93mm at 30°, 31.41±4.72 mm at 45°, 30.05±4.10mm at 60°, and 26.05±3.02mm at 90°. Significant length changes through flexion were observed (p < 0.0005), pairwise comparison found significant differences between 0° and 45° (p=0.025), 0° and 60° (p=0.012), and 0° and 90° (p=0.005). However, a significant negative correlation between degree of flexion and length was observed (r=-0.734, p < 0.0005).Conclusions:To our knowledge, this is the first study to describe the anatomy of the components of the lateral stabilizers including the LPFL, LPTL, and LPML. Reproducible locations on the femur and patella were observed for the two LPFL attachments. In addition, the attachment sites were found to have consistent distances to anatomic landmarks. Our results demonstrate that the LPFL length significantly correlates with flexion and maintains isometry through flexion, in contrast to the medial patellofemoral ligament, which has the greatest length changes in the first 20° of flexion.

When to Add Lateral Soft Tissue Balancing?

Lateral patellofemoral (PF) soft tissue abnormalities range from excessive lateral PF tightness (lateral patellar compression syndrome, lateral patellar instability and arthritis), to excessive laxity (iatrogenic lateral PF soft tissue insufficiency postlateral release). The lateral soft tissue complex is composed of the iliotibial band extension to the patella, the vastus lateralis tendon, the lateral PF ligament, lateral patellotibial ligament, and lateral patellomeniscal ligament, with intimate connections between those structures. To identify lateral retinaculum tightness or insufficiency the most important tests are the patellar glide test and patellar tilt test. Imaging aids in that evaluation relying mostly on the patella position assessed by radiographs, computed tomography, and magnetic resonance imaging with referencing to the posterior femoral condyles. Lateral retinaculum lengthening (preferred) or release may be added when there is excessive lateral retinaculum tightness. A lengthening may be performed using a minimally invasive approach without compromising the lateral patella restraint. Lateral retinaculum repair or reconstruction is indicated when there is lateral retinaculum insufficiency. Lateral retinaculum surgery to balance the medial/lateral soft tissue restraints, improves patellar positioning and clinical results.

Lateral Patellofemoral Ligament Reconstruction: Anatomy, Biomechanics, Indications and Surgical Techniques

With the exponential increase in the arthroscopic treatment of medial patellar instability through lateral sided “capsular” releases, the iatrogenic upsurge of lateral patellar dislocations has become more evident. Although few reports exist detailing the occurrence of this phenomenon due to traumatic or idiopathic etiologies, the vast majority (over 90%) are iatrogenic. Originally described by Kaplan and later by Reider, the lateral patellofemoral ligament (LPFL) constitutes one of the main stabilizers for medial patellar translation. Thus, understanding the anatomy and biomechanics of the LPFL is of utmost importance as reconstruction can potentially restore patellar instability and improve function in cases when this mechanism is compromised. However, few studies have sought to thoroughly describe the intricate anatomy and biomechanics of the LPFL to this end. The purpose of this article was to review the evidence on the anatomy of the LPFL and the lateral retinaculum, its biomechanical behavior, and previously reported surgical approaches to LPFL reconstruction.

Biomechanical Properties of the Lateral Patellofemoral Ligament: A Cadaveric Analysis.

Medial instability of the patellofemoral joint is a rare but known phenomenon; it may result from an incompetent lateral patellofemoral ligament (LPFL). However, biomechanical details of the ligament have not been the subject of scrutiny. The purpose of this study was to describe the biomechanical properties of the LPFL. Ten fresh-frozen human cadaveric knees were dissected to identify the LPFL. The ligament was harvested with a bone plug from the patella and the femoral surface and underwent axial loading to failure. Load to failure and location of failure were recorded. Regression analysis was performed to determine which anatomic variables (midsubstance width, femoral insertion width, patellar insertion width, or percent patellar articular surface of insertion) significantly influenced load to failure. Nine of the 10 specimens failed at the midsubstance of the ligament. The mean load to failure was 90±67 N. Logistical regression showed that midsubstance width was most correlated with load to failure, which approached but did not reach significance (P=.09). Studies are warranted to investigate the clinical consequences of medial patellar instability and the best repair or reconstruction techniques available. [Orthopedics. 2018; 41(2):e797-e801.].

Lateral Patellofemoral Ligament Reconstruction With a Gracilis Allograft

Isolated medial patellar subluxation (MPS), in the absence of a previous lateral retinacular release, is a poorly recognized clinical condition characterized by chronic anterior knee pain that is exacerbated with knee flexion. This type of patellar instability is often overlooked, and a high index of suspicion is needed for appropriate diagnosis and treatment. The purpose of this Technical Note is to describe a surgical technique to reconstruct the lateral patellofemoral ligament with an allograft gracilis tendon. By restoring stability to the lateral side of the patella, this minimally invasive technique successfully treats cases of isolated MPS.

Lateral Patellofemoral Ligament: An Anatomic Study.

Background:Medial instability of the patellofemoral joint is a rare but known phenomenon that may result from an incompetent lateral patellofemoral ligament (LPFL). Surgical reconstruction of the LPFL has been described. However, anatomic details of the ligament have not been the subject of scrutiny.Purpose:To describe the anatomic origin and insertion of the LPFL.Study Design:Descriptive laboratory study.Methods:Ten fresh-frozen, unpaired human cadaveric knees (mean age, 57 years) were dissected to identify the LPFL. The dissection was carried out by elevating the iliotibial band to expose the deep capsular layer of the knee joint, followed by a medial parapatellar approach to the knee. Then the quadriceps and patellar tendons were sectioned, and the LPFL was isolated by visualization and palpation. The LPFL was dissected to reveal its origin and insertion; these were measured with respect to the lateral epicondyle and the superior-inferior axis of the lateral patella, respectively.Results:On average, the LPFL had a variable point of origin in location as well as width about the lateral epicondyle. The LPFL originated, on average, 2.6 mm distal (range, 13.1 mm proximal to 11.4 mm distal) and 10.8 mm anterior (range, 7.3 mm posterior to 14.9 mm anterior) to the lateral epicondyle. The LPFL insertion on the patella was more reliably found to be about 45% (range, 23.7%-58.4%) of its lateral articular surface. The insertion on the patella was found to be in the middle third of the lateral patella.Conclusion:The LPFL has an origin that is variable but, on average, was found to be distal and anterior to the lateral epicondyle. The patella insertion was more reliably found to be in the middle third of the lateral patella. These anatomic relationships can help the surgeon reconstruct the LPFL in a more anatomic fashion.Clinical Relevance:Surgeons who are tasked with reconstruction of the LPFL of a patient with idiopathic medial instability or a previous aggressive lateral release of the knee may reference this article to perform an anatomic reconstruction of the LPFL. We hope that having anatomic landmarks for the reconstruction of this ligament permits the surgeon to operate in an efficient manner that allows for the optimal outcome. This is a rare surgical issue, and no studies are available that provide this information. The little information present in the literature does not provide measurements for anatomic reconstruction; rather, it is limited to descriptions of reconstruction techniques that indirectly provide stability on the lateral aspect of the knee.

An anatomic study of the lateral patellofemoral ligament

ObjectiveThe lateral patellofemoral ligament (LPFL) is part of the lateral retinaculum cut during arthroscopic or open release. We investigated its anatomic and morphometric characteristics. Materials and methodsWe identified the LPFL insertion point on the condyle in vertical and sagittal planes in 32 adult cadaveric knees. We measured its length and width at the insertion point. We located the midpoint of this point and measured from it to the distal and posterior condylar ends. We measured anterior-posterior and proximal-distal lateral condylar lengths. We evaluated the insertion point shape on the lateral femoral condyle. Degree of relationship between variables was assessed using Pearson's correlation coefficient. p < 0.05 was considered statistically significant. ResultsThe LPFL mean length was 23.2 mm, and mean width at the insertion point was 15.6 mm. Regarding its insertion into the lateral condyle, central insertions were more frequent (vertical plane: 53.1% central and sagittal plane: 75% central). A significant positive correlation was evident between the LPFL length and width at the insertion point (p = 0.05). Thus, the LPFL length was proportional to its width at the insertion point. A significant positive correlation was found between the anterior-posterior condylar length and width of the LPFL at the insertion point (p = 0.017). Therefore, greater anterior-posterior condylar length equates to a larger area of insertion on the condyle. ConclusionGreater width of the LPFL at the insertion point corresponds to greater LPFL and anterior-posterior lateral condylar lengths.